Switch to C89 comments in prep for making the whole codebase C89 compatible.

This should be whitespace/comment only changes and should produce the same
object code.
Merge pull request #105

71712b2 Switch to C89 comments in prep for making the whole codebase C89 compatible. (Gregory Maxwell)
Update README.md
Merge pull request #108

6c7f0c6 Update README.md (Pieter Wuille)
Add DETERMINISTIC to avoid line number/source dependent binaries

This will make it easier to detect changes without semantic impact.